Harnessing the power of the immune system to treat chronic infectious diseases or cancer is a major goal of immunotherapy. Active immunotherapy treatments are methods designed to activate the immune system to specifically recognize and destroy tumor or pathogen-infected cells. For over 200 years active immunotherapy approaches have been used to prevent numerous infectious diseases, including small pox, rabies, typhoid, cholera, plague, measles, varicella, mumps, poliomyelitis, hepatitis B and the tetanus and diphtheria toxins.
Active immunotherapy concepts are now being applied to develop therapeutic cancer vaccines with the intention of treating existing tumors or preventing tumor recurrence as well as for treatment and prevention of chronic viral infection. Many of these techniques have proven to successfully develop increased frequencies of immune cells in circulation that have the ability to specifically kill tumors or pathogen infected cells. However, despite the ability to generate immune cells reactive against tumor antigens, tumor escape mechanisms can overpower this immune response resulting in eventual tumor progression.
Active immunotherapy of cancer has been shown to be very effective in numerous rodent models. However, the clinically disappointing results of decades of immunotherapy trials of various types in humans have shown the immune system in humans does not perceive the threat/danger of human cancer cells as well as the immune system of rodent models of the same diseases.
The same is true of chronic viral infection. The innate immune response is able to slow down viral replication and activate cytokines which trigger the synthesis of antiviral proteins. The adaptive immune system neutralizes virus particles and destroys infected cells. However, viruses have developed a number of countermeasures to avoid immune attack and stay moving targets for the immune system.
There is a need to provide an active immunotherapy that is capable of overcoming tumor and viral immunoavoidance mechanisms and to train the human immune system to perceive the threat/danger of human cancer cells and viral infected cells resulting in an immune response which can eradicate tumors or pathogen-infected cells wherever they might be located in the body.